Face processing: studies in a series of Face processing: studies in a series of prosopagnosic patientsprosopagnosic patients

Louvain, Queen Square, November 2006Louvain, Queen Square, November 2006

Trevor BassTrevor BassAndrea ButlerAndrea Butler

Mariya V CherkasovaMariya V CherkasovaShaunak DeepakShaunak Deepak

Chris FoxChris FoxRebecca L HefterRebecca L Hefter

James M IntriligatorJames M IntriligatorJulian P KeenanJulian P KeenanGeorge MalcolmGeorge MalcolmSo Young MoonSo Young Moon

Numaan MalikNumaan MalikGalit YovelGalit Yovel

Jingher ZhaoJingher Zhao

Jason JS BartonJason JS BartonOlivier FelicianOlivier FelicianBeatrice de GelderBeatrice de GelderNouchine HadjikhaniNouchine HadjikhaniTodd HandyTodd HandyNancy KanwisherNancy KanwisherDara S ManoachDara S ManoachMargaret O’ConnorMargaret O’ConnorDan Z PressDan Z PressMax RiesenhuberMax Riesenhuber

Overview:Overview:

I. Starting pointsI. Starting points

II. ProsopagnosiaII. Prosopagnosia1. face perception1. face perception

• • A. facial spatial relationsA. facial spatial relations• • B. non-facial perceptionB. non-facial perception• • C. between- and within-object spatial processingC. between- and within-object spatial processing• • D. global/local processing D. global/local processing

2. face detection2. face detection3. face imagery 3. face imagery

III. SummaryIII. Summary

IV. Future directions…IV. Future directions…

STARTING POINT #1. Cognitive models of face processing propose a branching hierarchy of stages

early perceptualencoding

dynamic perceptualencoding

temporal invariantperceptual encoding

FRU (face recognition units)

PIN

expressionanalysis

directedanalysis

voiceother

name

input

semantic

info

STARTING POINT #2. Neuroimaging data STARTING POINT #2. Neuroimaging data show a network of face processing regions in show a network of face processing regions in human cortex.human cortex.

FusiformFusiformFaceFaceAreaArea

Superior TemporalSuperior TemporalSulcusSulcus

Occipital Face AreaOccipital Face Area

STARTING POINT #3. A variety of lesions cause prosopagnosia.STARTING POINT #3. A variety of lesions cause prosopagnosia.

8 adult-onset lesions:8 adult-onset lesions:

5 bilateral5 bilateral

1 bilateral 1 bilateral anterior temporalanterior temporal traumatrauma

2 bilateral 2 bilateral occipito-temporaloccipito-temporal trauma, gunshottrauma, gunshot

2 right 2 right anterior temporal/occipitalanterior temporal/occipital small left temporal lesionssmall left temporal lesions

trauma, encephalitistrauma, encephalitis

3 unilateral3 unilateral

3 right 3 right occipito-temporaloccipito-temporal stroke (2), tumorstroke (2), tumor

3 childhood-onset lesions:3 childhood-onset lesions:head traumahead traumaoccipital polymicrogyriaoccipital polymicrogyriarespiratory arrest, posterior gyral atrophyrespiratory arrest, posterior gyral atrophy

Is there a relation between cognitive models and anatomic data?

Can prosopagnosia tell us something about structure-function correlations?

early perceptualencoding

dynamic perceptualencoding

temporal invariantperceptual encoding

FRU

PIN

expressionanalysis

directedanalysis

voiceother

name

input

semantic

info

occipital occipital face face area?area?

fusiform fusiform face face area?area?

anterior anterior temporal?temporal?

superior superior temporal temporal sulcus?sulcus?

I. PROSOPAGNOSIAI. PROSOPAGNOSIA

“The inability to recognize previously seen faces, with relative sparing of other perceptual, cognitive and memory functions.”

Broad Subtypes:

1. Apperceptive - failure to generate a sufficiently accurate percept to allow a successful match to stores of previously seen faces.

2. Associative - accurate percept, but failure to match because of loss of facial memory stores or disconnection from them.

Family of subtypes corresponding to defects at different stages in a cognitive model of face processing.

1. PERCEPTION IN PROSOPAGNOSIA

Q. What kind of perceptual deficit can affect recognition of individual faces yet spare basic-level object recognition ?

object recognition theories:

a. ‘entry-level’ recognition, satisfied by coarse categorical structural descriptions (i.e. “recognition by component” theory, geons, edge-based)

b. precise metrical (coordinate) analysis for exemplar recognition

coordinate change

categorical change

• Faces all share the same basic structure, with the same features (two eyes, nose, mouth) in the same arrangement (e.g. eyes above nose)• What distinguishes one face from another are subtler variations in the precise

metrical structure and arrangement of these elements.

Coordinate(2nd order spatial relation)change

Categorical (1st order spatial relation)change

1.A) Perception of spatial relations in prosopagnosia1.A) Perception of spatial relations in prosopagnosia

What is the perceptual defect in prosopagnosia ?What is the perceptual defect in prosopagnosia ?

••Perceiving precise Perceiving precise structural coordinates (e.g. second-order spatial structural coordinates (e.g. second-order spatial relations)relations) may be important in recognizing specific exemplars of may be important in recognizing specific exemplars of complex 3-D structures.complex 3-D structures.

••Normal subjects have difficulty recognizing Normal subjects have difficulty recognizing inverted facesinverted faces, and , and studies show that this is accompanied by difficulty perceiving the studies show that this is accompanied by difficulty perceiving the spatial relations of facial features.spatial relations of facial features.

Barton JJS, Keenan J, Bass T. Discrimination of spatial relations and features in Barton JJS, Keenan J, Bass T. Discrimination of spatial relations and features in faces: effects of inversion and viewing duration. Brit J Psychol 2001;92: 527.faces: effects of inversion and viewing duration. Brit J Psychol 2001;92: 527.

Barton JJS, Deepak S, Malik N. Attending to faces: change detection, familiarization, Barton JJS, Deepak S, Malik N. Attending to faces: change detection, familiarization, and inversion effects. Perception 2003; 32: 15.and inversion effects. Perception 2003; 32: 15.

?

1.A) Perception of spatial relations in prosopagnosia1.A) Perception of spatial relations in prosopagnosia

What is the perceptual defect in prosopagnosia ?What is the perceptual defect in prosopagnosia ?

••Perceiving precise Perceiving precise structural coordinates (e.g. second-order spatial structural coordinates (e.g. second-order spatial relations)relations) may be important in recognizing specific exemplars of may be important in recognizing specific exemplars of complex 3-D structures.complex 3-D structures.

••Normal subjects have difficulty recognizing Normal subjects have difficulty recognizing inverted facesinverted faces, and , and studies show that this is accompanied by difficulty perceiving the studies show that this is accompanied by difficulty perceiving the spatial relations of facial features.spatial relations of facial features.

Q. Are prosopagnosics impaired at perceiving ‘coordinate’ spatial Q. Are prosopagnosics impaired at perceiving ‘coordinate’ spatial relations?relations?

Barton JJS, Keenan J, Bass T. Discrimination of spatial relations and features in Barton JJS, Keenan J, Bass T. Discrimination of spatial relations and features in faces: effects of inversion and viewing duration. Brit J Psychol 2001;92: 527.faces: effects of inversion and viewing duration. Brit J Psychol 2001;92: 527.

Barton JJS, Deepak S, Malik N. Attending to faces: change detection, familiarization, Barton JJS, Deepak S, Malik N. Attending to faces: change detection, familiarization, and inversion effects. Perception 2003; 32: 15.and inversion effects. Perception 2003; 32: 15.

base face eye colour lightened by 12%

mouth shifted up by 6 pixels interocular distancedecreased by 10 pixels

Barton JJS, Press DZ, Keenan JP, O’Connor M. Lesions of the fusiform face area Barton JJS, Press DZ, Keenan JP, O’Connor M. Lesions of the fusiform face area impair perception of facial configuration in prosopagnosia. Neurology 2002; 58: 71.impair perception of facial configuration in prosopagnosia. Neurology 2002; 58: 71.

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Results: perception of spatial relations:Results: perception of spatial relations:

1a. The “geometry effect”: Integrating spatial relations across the face:1a. The “geometry effect”: Integrating spatial relations across the face:

S.008, with S.008, with anterior temporal lesionsanterior temporal lesions, does relatively well at , does relatively well at discriminating single spatial relations (mouth or eye) in a target face.discriminating single spatial relations (mouth or eye) in a target face.

Q. How does she integrate spatial information across the whole face?Q. How does she integrate spatial information across the whole face?

Consider ‘aspect ratio’ of eyes to mouth.Consider ‘aspect ratio’ of eyes to mouth.

Combined moves of eyes and mouth can preserve the aspect ratio or Combined moves of eyes and mouth can preserve the aspect ratio or distort it.distort it.

-400

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upright

inverted

““GEOMETRY EFFECT”:GEOMETRY EFFECT”:

Results:Results:

Normal subjects are faster and more accurate at discriminating more distorting combinations than less distorting ones in upright faces,

BUT NOT in inverted faces.

S.008 does not show a significant ‘geometry effect’.

Hence she perceives spatial changes but does not integrate this information across the face.

(more distorting - less distorting)

1.B) Non-facial perception in apperceptive prosopagnosia:1.B) Non-facial perception in apperceptive prosopagnosia:

““Low level” perceptionLow level” perception

• • static contrast sensitivitystatic contrast sensitivity

• • luminance luminance

• • saturationsaturation

• • spatial resolutionspatial resolution

• • dot displacementdot displacement

• • curvature discriminationcurvature discrimination

NeuropsychologyNeuropsychology

• • visual object and space visual object and space perception batteryperception battery

• • Ghent overlapping figuresGhent overlapping figures

• • Benton line orientationBenton line orientation

Within-categoryWithin-category

• • vegetable identificationvegetable identification

• Most patients had difficulty with fruit/vegetable identificationnormal 0-3 errors patients 3-20 errors

• Most consistent defects in occipitotemporal lesions were:- reduced mid-high spatial freq. (4.2 - 8.4 cycles/°) contrast sensitivity- reduced perception of dot displacement

• Bilateral lesions reduced thresholds for saturation perception, scores for overlapping figures.

• Curvature and line orientation impaired in S.006 only, who had the

most difficulty with basic-level object recognition.

Barton JJS, Cherkasova, MV, Press DZ, Intriligator JM, O’Connor M. Perceptual Barton JJS, Cherkasova, MV, Press DZ, Intriligator JM, O’Connor M. Perceptual functions in prosopagnosia. Perception 2004; 33: 939.functions in prosopagnosia. Perception 2004; 33: 939.

1.B) Non-facial perception in apperceptive prosopagnosia1.B) Non-facial perception in apperceptive prosopagnosia

1.C) ‘Within-object’ versus ‘between-object’ spatial representations:1.C) ‘Within-object’ versus ‘between-object’ spatial representations:

Prosopagnosics fail at the “coordinate” spatial relations in faces or abstract Prosopagnosics fail at the “coordinate” spatial relations in faces or abstract dot patterns. What about other “visuospatial” functions?dot patterns. What about other “visuospatial” functions?

Within-object and between-object spatial representations may be Within-object and between-object spatial representations may be functionally and anatomically distinct:functionally and anatomically distinct:• • Between-object perception can show the opposite direction of neglect to Between-object perception can show the opposite direction of neglect to within-object neglect.within-object neglect.

Humphreys G. Phil Trans R Soc Lond B 1998;353:1341Humphreys G. Phil Trans R Soc Lond B 1998;353:1341

• • Patient with bi-parietal lesions (Patient with bi-parietal lesions (dorsal pathwaydorsal pathway) has normal within-object ) has normal within-object but abnormal between-object spatial judgments.but abnormal between-object spatial judgments.

Cooper A, Humphreys G. Neuropsychologia 2000;38:723Cooper A, Humphreys G. Neuropsychologia 2000;38:723

Q. Do our patients (with Q. Do our patients (with ventral pathwayventral pathway lesions) have the opposite lesions) have the opposite dissociation: abnormal within-object but normal between-object spatial dissociation: abnormal within-object but normal between-object spatial

perception?perception?

Within-face spatial processingWithin-face spatial processing Between-face spatial processingBetween-face spatial processing

Which face is different?Which face is different? Which face is furthest away from Which face is furthest away from the other two?the other two?

within

Barton JJS, Cherkasova MV. Impaired spatial coding within-objects but not between-objects in prosopagnosia. Neurology 2005; 65: 270.

Conclusion: prosopagnosic subjects have good between-object perception.

Results:Results: within - objectwithin - object between - objectbetween - object

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between-faceswithin-faces

chance

Q. When does a between-object relation become a within-object one?Q. When does a between-object relation become a within-object one?

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Task 1: which apex is further away from the other two?Task 1: which apex is further away from the other two?

Task 2 (Bálint’s patient): is this triangle symmetric or asymmetric?Task 2 (Bálint’s patient): is this triangle symmetric or asymmetric?

(A ‘competition’ between spatial representations)

discsonly

kanisza line+discs

lineonly

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S.B001

PROSOPAGNOSIA

BALINT'S SYNDROME

unilateral

bilateral

control

Is there an ‘H’ ?

1.D) Global/local perception:1.D) Global/local perception:

If there is a ‘holistic’ deficit in face If there is a ‘holistic’ deficit in face perception, some postulate that perception, some postulate that this should also be revealed as a this should also be revealed as a failure to perceive ‘global’ level failure to perceive ‘global’ level information.information.

Q. Do they fail to show effects of Q. Do they fail to show effects of the global level of hierarchical the global level of hierarchical Navon letters?Navon letters?

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apperceptive prosopagnosia

Global/localGlobal/local

8 apperceptive 8 apperceptive prosopagnosic prosopagnosic patients patients (1 developmental)(1 developmental)

Longer RT in general, Longer RT in general, but but normal pattern of normal pattern of global influences.global influences.

2. FACE DETECTION IN PROSOPAGNOSIA

- de Gelder postulated five separate face processing mechanisms, in which face detection and face recognition are distinct..-Riesenhuber’s computational models suggest that detection and recognition are merely points on a perceptual continuum.

Are prosopagnosic subjects normal at detecting faces?RUBIN’S VASE EXPERIMENT:

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3. FACE IMAGERY IN PROSOPAGNOSIA3. FACE IMAGERY IN PROSOPAGNOSIA

How do we diagnose How do we diagnose associative prosopagnosiaassociative prosopagnosia??

Indirect conclusion - “if perception seems normal, must be Indirect conclusion - “if perception seems normal, must be associative”associative”

• • What we need is a method of assessing the status of facial What we need is a method of assessing the status of facial memory stores, without having to go through a perceptual route:memory stores, without having to go through a perceptual route:………………... ... imageryimagery..

• • What kind of face imagery ? Is there a distinction between local What kind of face imagery ? Is there a distinction between local features and ‘holistic’ or overall facial configuration?features and ‘holistic’ or overall facial configuration?

Face imagery questionnaireFace imagery questionnaire

37 questions, AFC 2 choice.31 controls, not at ceiling (93% correct)

19 feature-related imageryWho has the more prominent nose? Meryl Streep Nicole KidmanWho has a moustache? Martin Luther King Jr Louis Armstrong

18 ‘global’ face shape imageryWho has the narrower face? Cher Martha StewartWho has the more angular face? George Washington Abraham Lincoln

calculate binomial limits of chance (does it exist?), and95% prediction interval for normal imagery (is it impaired?)

Imagery resultsImagery results

mean s.004 s.010 s.005 s.006 s.009 s.001 s.003 s.008 s.007 s.0110.4

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bilateraloccipitotemporal

rightoccipitotemporal

anteriortemporal, plus

developmentalnormal

*

*

**

Summary - imagery results:Summary - imagery results:

• • bilateral occipitotemporalbilateral occipitotemporal lesions impair but do not abolish face lesions impair but do not abolish face imagery.imagery.

• • unilateral right-sided occipitotemporal unilateral right-sided occipitotemporal lesions impair imagery for lesions impair imagery for global facial structure more than imagery for features. global facial structure more than imagery for features.

• • anterior temporalanterior temporal lesions abolish face imagery. lesions abolish face imagery.

Barton JJS, Cherkasova M. Face imagery and its relation to perception and covert Barton JJS, Cherkasova M. Face imagery and its relation to perception and covert recognition in prosopagnosia. Neurology 2003; 61: 220-225.recognition in prosopagnosia. Neurology 2003; 61: 220-225.

III. SUMMARY (a) Tentative structure-function correlations:

• bilateral occipitotemporal lesions (in the region of the FFA): have a severe failure to perceive “coordinate” spatial relations,are only mildly impaired face imagery, consistent with an apperceptive prosopagnosia.

• right occipitotemporal lesions: are similar to bilateral ones, except for preserved imagery for facial features, and less severe prosopagnosia (d’ measures).

• anterior temporal lesions: markedly impair face imagery, with only subtle (integrative?) effects on perceiving spatial relations, consistent with an associative prosopagnosia.

III. SUMMARY (b) Characteristics of the apperceptive defect:

• • This defect in processing structure affects This defect in processing structure affects other ‘non-face’ stimuliother ‘non-face’ stimuli, and may , and may be one mechanism by which recognition of exemplars of other object classes be one mechanism by which recognition of exemplars of other object classes is impaired.is impaired.

• This defect is specific for ‘within-object’ spatial representations.

• • Reduced high spatial frequency Reduced high spatial frequency contrast sensitivitycontrast sensitivity may play a role. may play a role.

• Global/local processing is not affected.

• Figure-ground assignment is impaired and more difficult with faces.

Do these conclusions have predictive power?

RC: 25 year old manHSV Encephalitis 2 years ago.

BEHAVIOURAL TESTING:Face familiarity: impairedFamous faces: d’ = 0.61 (N>2.9)Relatives’ faces: d’ = 0.87

Perception of faces - goodBenton Face recognition test = 45/54Spatial relations : 2 second; unlimited time

- eye 80% (N> 73); 93% (N> 68)- mouth 70% (N> 72); 89% (N> 55)

Morphed faces - same view = 77.8% (N>78)- varying view = 62.5% (N>57)

Short term memory for faces - poorWarrington Recognition Memory test faces = 27/50 ; words = 45/50

RC’s behavioural data are most consistent with an associative prosopagnosia:

Prediction: RC’s neuroimaging will show:

1. Bilateral anterior temporal lesions

2. Sparing of FFA….

….BUT is FFA spared?

PLAN: do an fMRI experiment on RC

fMRI confirms that it is:

Result: Result:

RC does have an FFA,RC does have an FFA,

ANDAND

it shows adaptation it shows adaptation effects to identity.effects to identity.

This supports the This supports the hypothesis that the FFA hypothesis that the FFA is involved in is involved in perception of facial perception of facial structure, and that its structure, and that its loss leads to loss leads to apperceptive apperceptive prosopagnosia.prosopagnosia.

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Event-related potentials in RC also show a face-selective N170 response Event-related potentials in RC also show a face-selective N170 response in his right occipitotemporal region, and possibly a distinction between in his right occipitotemporal region, and possibly a distinction between familiar and anonymous faces in later responsesfamiliar and anonymous faces in later responses

objects

N170

familiar facesanonymous faces

Left occipitotemporal Right occipitotemporal

Future directions:

Perception of other facial structural data?

Future directions:

Why are some right PCA patients prosopagnosic and others not?

S.009 prosopagnosia P.001 non-prosopagnosic

Hadjikhani & de Gelder Yovel & Kanwisher

“I was at a conference and I saw this other person walking. I thought it was probably someone I knew and so I smiled at them and started to greet them, only to realize that it was my own face and I was looking at a mirrored wall.”

(LH - subject 011)

http://www.neuroophthalmology.ca/UBCNeuroOp/JBarton/FrJBhome.html

NORMAL PERCEPTUAL STUDIESNORMAL PERCEPTUAL STUDIESBarton JJS, Keenan JP, Bass T. Discrimination of spatial relations and features in faces: effects of inversion and viewing duration. Barton JJS, Keenan JP, Bass T. Discrimination of spatial relations and features in faces: effects of inversion and viewing duration. Brit J PsycholBrit J Psychol 2001; 92: 527-49. 2001; 92: 527-49.Barton JJS, Deepak S, Malik N. Attending to faces: change detection, familiarisation and inversion effects. Barton JJS, Deepak S, Malik N. Attending to faces: change detection, familiarisation and inversion effects. PerceptionPerception 2003; 32: 15- 2003; 32: 15-28.28.Malcolm GL, Leung C, Barton JJS. Regional variation in the inversion effect for faces: different patterns for feature shape, spatial Malcolm GL, Leung C, Barton JJS. Regional variation in the inversion effect for faces: different patterns for feature shape, spatial relations, and external contour. relations, and external contour. PerceptionPerception 2004; 33: 1221-31. 2004; 33: 1221-31.Barton JJS, Radcliffe N, Cherkasova MV, Edelman J, Intriligator JM. Information processing during face recognition: the effects of Barton JJS, Radcliffe N, Cherkasova MV, Edelman J, Intriligator JM. Information processing during face recognition: the effects of familiarity, inversion and morphing on scanning fixations. familiarity, inversion and morphing on scanning fixations. PerceptionPerception 2006: 353:1089-105 2006: 353:1089-105Fox CJ, Barton JJS. What is adapted in face adaptation? The neural representations of expression in the human visual system. Fox CJ, Barton JJS. What is adapted in face adaptation? The neural representations of expression in the human visual system. Brain ResBrain Res, in press, in pressPROSOPAGNOSIC STUDIESPROSOPAGNOSIC STUDIESBarton JJS, Cherkasova M, O’Connor M. Covert and overt recognition in acquired and developmental prosopagnosia. Barton JJS, Cherkasova M, O’Connor M. Covert and overt recognition in acquired and developmental prosopagnosia. NeurologyNeurology 2001; 57: 1161-7.2001; 57: 1161-7.Barton JJS, Press DZ, Keenan, JP, O’Connor M. Lesions of the fusiform face area impair perception of facial configuration in Barton JJS, Press DZ, Keenan, JP, O’Connor M. Lesions of the fusiform face area impair perception of facial configuration in prosopagnosia. prosopagnosia. Neurology Neurology 2002; 58: 71-8.2002; 58: 71-8.Barton JJS, Cherkasova M, Press DZ, Intriligator J, O’Connor M. Developmental prosopagnosia: a study of three patients. Barton JJS, Cherkasova M, Press DZ, Intriligator J, O’Connor M. Developmental prosopagnosia: a study of three patients. Brain and Brain and CognitionCognition 2003; 51: 12-30. 2003; 51: 12-30.Barton JJS, Cherkasova M. Face imagery and its relation to perception and covert recognition in prosopagnosia. Barton JJS, Cherkasova M. Face imagery and its relation to perception and covert recognition in prosopagnosia. NeurologyNeurology 2003; 2003; 61: 220-225.61: 220-225.Barton JJS, Zhao J, Keenan JP. Perception of global facial geometry in the inversion effect and prosopagnosia. Barton JJS, Zhao J, Keenan JP. Perception of global facial geometry in the inversion effect and prosopagnosia. NeuropsychologiaNeuropsychologia 2003; 41: 1703-1711.2003; 41: 1703-1711.Joubert S, Felician O, Barbeau E, Sontheimer A, Barton JJS, Ceccaldi M, Poncet M. Impaired configurational processing in a case Joubert S, Felician O, Barbeau E, Sontheimer A, Barton JJS, Ceccaldi M, Poncet M. Impaired configurational processing in a case of progressive prosopagnosia associated with right temporal lobe atrophy. of progressive prosopagnosia associated with right temporal lobe atrophy. BrainBrain 2003; 126: 2537-50. 2003; 126: 2537-50.de Gelder B, Frissen I, Barton J, Hadjikhani N. A modulatory role for facial expressions in prosopagnosia. de Gelder B, Frissen I, Barton J, Hadjikhani N. A modulatory role for facial expressions in prosopagnosia. Proc Nat Acad SciProc Nat Acad Sci 2003: 2003: 100: 13105-10.100: 13105-10.Barton JJS, Cherkasova MV, Hefter R. The covert priming effect of faces in prosopagnosia. Barton JJS, Cherkasova MV, Hefter R. The covert priming effect of faces in prosopagnosia. NeurologyNeurology 2004; 63: 2062-8. 2004; 63: 2062-8.Barton JJS, Cherkasova M, Press DZ, Intriligator J, O’Connor M. Perceptual function in prosopagnosia. Barton JJS, Cherkasova M, Press DZ, Intriligator J, O’Connor M. Perceptual function in prosopagnosia. PerceptionPerception 2004; 33: 939- 2004; 33: 939-56.56.Barton JJS, Cherkasova MV. Impaired spatial coding within-objects but not between-objects in prosopagnosia. Barton JJS, Cherkasova MV. Impaired spatial coding within-objects but not between-objects in prosopagnosia. NeurologyNeurology 2005; 65: 2005; 65: 270-4.270-4.Barton JJS. Disorders of face perception and recognition. Barton JJS. Disorders of face perception and recognition. Neurologic ClinicsNeurologic Clinics 2003; 21: 521-548. 2003; 21: 521-548.AUTISM SPECTRUM STUDIESAUTISM SPECTRUM STUDIESBarton JJS, Cherkasova MV, Hefter R, Cox TA, O’Connor M, Manoach DS. Are patients with social developmental disorders Barton JJS, Cherkasova MV, Hefter R, Cox TA, O’Connor M, Manoach DS. Are patients with social developmental disorders prosopagnosic? Perceptual heterogeneity in the Asperger and socio-emotional processing disorders. prosopagnosic? Perceptual heterogeneity in the Asperger and socio-emotional processing disorders. BrainBrain 2004; 127: 1706-16. 2004; 127: 1706-16.Hefter R, Manoach DS, Barton JJS. Perception of facial expression and facial identity in patients with developmental social Hefter R, Manoach DS, Barton JJS. Perception of facial expression and facial identity in patients with developmental social processing disorders. processing disorders. NeurologyNeurology 2005; 65: 1620-5. 2005; 65: 1620-5.